This is high quality natural PTFE Teflon tubing. Great for insulating and protecting bare wire/leads. Operating temps from 500°F down to -454°F. Internal diameter measures 0.129"-0.139" (3.28mm-3.53mm) with a wall thickness of 0.012"- 0.018" (0.30mm-0.46mm). Priced and sold by the foot (0.305 meter).